Analysis of the Collaborative Perinatal Project (CPP) data continues in the area of maternal infection. (The CPP is a prospective study of approximately 60,000 gravidae and the follow-up of their children through the seventh year of life.) Two primary methodologies have been used, a prospective and a case control approach. Since serological confirmation of all of the common infections occurring during pregnancy on all women in the project would not have been feasible, a case control design has been implemented assessing the titer of 11 antigens in women with abnormal children, in comparison with matched control women with normal children. This study did not show any clear association between infection during the second and third trimester of pregnancy and specific damage to the child. A prospective study of the association of childhood morbidity with maternal antibody level to toxoplasmosis and a descriptive study of the distribution of titers and frequency of seroconversions by race and age of gravidae for various antigens in a population of pregnant women, are in progress or have been completed. The prospective serological study of toxoplasmosis and its relationship with pregnancy outcome, based on the first 23,000 pregnancies in the study, has shown increases in the risk of deafness, microcephaly and low IQ among children born to women with high maternal antibody to toxoplasmosis. Manuscripts reporting the results of the toxoplasmosis study and the study of serologically confirmed infections have been submitted for publication.